python-future is now deprecated

# Details
python-future is now deprecated and does not work with python 3.12. From gentoo's package notes:
```
# Deprecated, doesn't work with python 3.12. Unmaintained with last
# serious release in 2019, and another release in 2024 that claims
# to support python 3.12 but fails tests if you actually do. No
# route to making it work with python 3.13 at all, and upstream
# explicitly states that future "like Python 2, is now done". The
# package is entirely redundant to packages not supporting python
# 2 anymore, and the ones that do support it should be using
# dev-python/six instead, anyways. Bug #888271
# Removal on 2024-04-13.
```

# Impact
If this project does depend on `future` (as stated in requirements-python3x.txt), it will stop working or present with issues starting with python 3.12.

# NeedBy
`future` library should be purged from this project before distributions ship with python 3.12 or potentially 3.13 as the default. Until fixed, users should be instructed to use a virtualenv with